3 



pulchella (Heidd \993), and Penstet}w?i le/nhiensis {ShtWy 1987, 1990). Subsequent multi-species 

 survey studies conducted in southwestern Montana have helped to document the breadth of botanical 

 biodiversity, to determine habitat requirements, and to identify potential habitat in other study areas, 

 e.g., Bannack State Park (Vanderhorst 1995); Highland Mountains (Lesica 1992); Tendoy Mountains 

 (Vanderhorst and Lesica 1994, Vanderhorst 1995); Horse Prairie (Vanderhorst 1995); and the Centennial 

 Valley (Culver 1993). 



The individual study areas are described in the following text and are presented in this same sequence 

 throughout the report. 



Big Hole Study Area 



The Big Hole Study Area lies in the outlying McCartney Mountain and its foothills at the south end of 

 the Highland Mountains, north of the large bend in the Big Hole River (Figure 2). It is mainly in 

 Beaverhead County, extending into Madison County, and barely into Silver Bow County. The area 

 consists of nearly contiguous BLM lands interrupted at times by patented mining claims or private lands 

 (usually along the rivers and roads). 



The lowest point, <5000 ft., is found along the Big Hole River; the highest point, >8000 ft., is found in 

 the Highland Mountains at the boundary with the Deerlodge National Forest. Parent materials in the 

 Highland foothills are predominantly undifferentiated Tertiary sediments, with Precambrian gneiss, 

 schists, and related rocks. Areas with Colorado Shale, Kootenai Formation, and Boulder Batholith are 

 centered around McCartney Mountain (Ross et al. 1955). 



Vegetation of the Big Hole Study area is predominantly grassland and sagebrush steppe, grading into 

 forest types with Douglas fir and lodgepole pine in the Highland Mountains and around McCartney 

 Mountain. The BLM lands skirt the Big Hole valley and its floodplain vegetation, with steep 

 escarpments occurring along the western segment. 



Grasshopper Study Area 



The Grasshopper Study Area lies in the foothills at the south end of the Pioneer Mountains, Beaverhead 

 County (Figure 2). Grasshopper Creek is the largest central landmark feature in the study area, though 

 the study area extends beyond the Grasshopper Creek watershed. The Beaverhead National Forest lies 

 at higher elevations to the north, and Bannack State Park is located at the western edge of the study area. 

 State school lands and private lands interrupt the otherwise continuous study area. 



Amongst the study areas, this section has the most extensive area of limestone surface geology. This is 

 of particular significance, as several of the target species are calciphiles ("calcium-loving" plants). 

 Where these limestone beds come into contact with igneous intrusive rocks are found the largest lode 

 deposits of precious minerals. The lowest points are <5500 ft. along the Grasshopper Creek and 

 Beaverhead River; the highest points are >6500 ft. on Henneberry Ridge. The entire area contains a wide 

 variety of sedimentary rocks oriented in bands that are undifferentiated members from the Cambrian, 

 Mississippian (including limestones), Pennsylvanian, Pemiian, and Triassic Eras. The prevailing 

 outcrops are undifferentiated Tertiary sediments, interrupted by Tertiary volcanic rock (Ross 1955). 



